Add FTP credentials management and UI enhancements

- Implement migration script to add ftp_username and ftp_password columns to nl43_config table.
- Create set_ftp_credentials.py script for updating FTP credentials in the database.
- Update requirements.txt to include aioftp for FTP functionality.
- Enhance index.html with FTP controls including enable, disable, check status, and list files features.
- Add JavaScript functions for handling FTP operations and displaying file lists.

.gitignore

@@ -1 +1,2 @@
 /manuals/
+/data/